DieBieCO (ChargeOnly BMS) development blog.

Dear all, the time has come to do an attempt to make an open source charge only BMS which can interface over CAN bus with the VESC ( BMS interface of the VESC ), a Metr.at module and many other stuff who are already working with the DieBieMS (protocol will be very close, if not equal ).

For an extremely long time I have been procrastinating this project because I wanted to make a BMS that fit all the needs of every application from very small to very big LEV’s. However I always ran into cost and complexity which also resulted in a ver big sized BMS once more. I long aimed to add BLE, isolated current measurement and isolated CAN, main current switching like the DieBieMS but the most recent Esk8 trends remove the need of all of them. We no longer need BLE on a BMS since most of use already interface directly with the VESC trough BLE or trough an added dongle like the Metr.at. With the resent implementation of main current switching in the ESC’s directly we also no longer need that to be done by the BMS, although ideally the BMS would protect the battery against a load at all cost, we sort of already accepted in charge only builds that when configured correctly it is “ok” enough to have the ESC in control. This is only for the DIY marked, for consumer electronics this is of course not acceptable and does also not comply with UN test requirements. The recent implementation of listening to a BMS in the VESC firmware motivated me / made me accept that ChargeOnly can be acceptable for DIY.

Now that I have concluded that this is acceptable I am going to attempt to make an affordable charge only solution of which the hardware and firmware sources will be full open, just like the DieBieMS, I will also attempt to make it a size that is compelling to be easily implemented in compact builds. A very important thing which I would like to remain implemented on the BMS is a method to measure the battery current to be able to estimate the internal resistance, SoC, SoH and usage in general of the pack. So the main battery current will still run trough the BMS in the ground side. Charge current will be switched and controlled high side. I will also include a USB PD interface to allow for a future USB PD DCDC converter extension to use the Esk8 battery as a power bank.

Over the course of the upcoming months I will be share the progress here and will be curious on your feedback. I am open to mechanical size critics but also open for advice for aluminium CNC modification parties who could, if they want, can eventually develop a mounting / cooling solution.

My aim for the BMS is to work with chargers up to 30Amps (switch and control) and discharge currents up to 150A (only measure). The operational voltage will be from 6Series connected cells up to 16Series.


This will be good for sure

I was riding earlier today and thinking about the error that we probably have in energy usage due to the VESC only estimating it, will be cool to see how they compare


Awesome news!

Thanks so much for your continued contributions & dedication to this work. Seriously impressive @JTAG


Yay for more charge-only smart BMS! Will be following closely! Thanks @JTAG!


Project died?

Guessing its not his top prio :slight_smile:

ooor its already finnished :smiley:

No absolutely not :innocent: :innocent:, the foundations are made for a wide range of applications and am currently testing some chipsets to make it very affordable as well ( I want this BMS to be close in price to the asian BMSes, which is challenging :upside_down_face:). The BMS can be used in small/medium sized electric vehicles. For me this is a side project which is quite time consuming and not cheap :sweat_smile:. All will be available for free for everyone ( no return of investment ), so please consider that that also contributes to the timeline and progress.

Priority got a bit lowered because a very exciting RF project came in between which is for the esk8 market ( I got asked to do some work by another forum member ), and those prototypes look promising as well.

In the upcoming months some of the results will come to the surface, I already shared a glimpse of the new BMS in the no words just pictures thread.


Any progress on this one?

Idk when the updated pd design will be released, but 240w is quite a lot.
Spec quotes 50v @ 5a
I would consider usb c charging now aswell ;))


I thought the new USB spec was 48V? Is it 50V?

Well if I read correctly 50.9V may even be possible

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It looks like 48V is the maximum charge voltage that can be negotiated

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I don’t exactly know how usb PD works but to me looks like register bit 11b sets output to 50v

and there is obvously some tolerance, that’s where the 50.9v max comes in. (I might me all wrong tho)